A power amplifier (PA) is usually at an end of a transmission link of a base station in a wireless communication system, and is an important component of a base station.
With development of communications technologies, a base station needs to support services of a plurality of frequency bands simultaneously. Therefore, the base station needs to implement a function of simultaneously transmitting signals of a plurality of frequency bands (for example, 1.8 gigahertz (GHz)+2.1 GHz, or 1.8 GHz+2.1 GHz+2.6 GHz) by using a multi-band power amplifier.
Types of current power amplifiers include a single-input structure and a dual-input structure. For a power amplifier of a single-input structure (also referred to as a single-input power amplifier), a compromise among output power, working efficiency, and a signal bandwidth needs to be made, and therefore the output power and the working efficiency are not high. Compared with the single-input power amplifier, a power amplifier of a dual-input structure (also referred to as a dual-input power amplifier) can increase output power and working efficiency.
Because a power amplifier that amplifies multi-band signals needs to ensure a relatively high broadband requirement, if a single-input power amplifier is used to process the multi-band signals, higher output power and working efficiency need to be sacrificed while the broadband requirement is satisfied. Therefore, a dual-input power amplifier is an ideal choice. How to process a radio frequency signal to obtain a multi-band signal or a broadband signal that can optimize output power and working efficiency of the dual-input power amplifier is a problem that urgently needs to be resolved by a person skilled in the field of wireless communications.